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    <title>ShellCheck: SC2200 – Brace expansions don't work as operands in `[ ]`. Use a loop.</title>
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    <h1>SC2200 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2200">See this page on GitHub</a>
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    <h2 id="brace-expansions-dont-work-as-operands-in---use-a-loop">Brace
expansions don't work as operands in <code>[ ]</code>. Use a loop.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2200.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">[</span> <span class="st">&quot;</span><span class="va">$file</span><span class="st">&quot;</span> <span class="ot">=</span> index.<span class="dt">{htm</span><span class="op">,</span><span class="dt">html</span><span class="op">,</span><span class="dt">php}</span> <span class="bu">]</span> <span class="kw">&amp;&amp;</span> <span class="bu">echo</span> <span class="st">&quot;This is the main file&quot;</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2200.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> main <span class="kw">in</span> index.<span class="dt">{htm</span><span class="op">,</span><span class="dt">html</span><span class="op">,</span><span class="dt">php}</span></span>
<span id="cb2-2"><a href="SC2200.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="cf">do</span></span>
<span id="cb2-3"><a href="SC2200.html#cb2-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">[</span> <span class="st">&quot;</span><span class="va">$file</span><span class="st">&quot;</span> <span class="ot">=</span> <span class="st">&quot;</span><span class="va">$main</span><span class="st">&quot;</span> <span class="bu">]</span> <span class="kw">&amp;&amp;</span> <span class="bu">echo</span> <span class="st">&quot;This is the main file&quot;</span></span>
<span id="cb2-4"><a href="SC2200.html#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="cf">done</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>Brace expansions in <code>[ ]</code> will expand to a sequence of
words. Operators work on single words.</p>
<p>The problematic code is equivalent to
<code>[ "$file" = index.htm index.html index.php ]</code>, which is
invalid syntax. A typical error message is
<code>bash: [: too many arguments</code> or
<code>dash: somefile: unexpected operator</code>.</p>
<p>Instead, use a <code>for</code> loop to iterate over values, and
apply your condition to each.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>None.</p>
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